# 打印 1~ 20 的整数, 每行打印 5 个， 打印 四行, 如:
# 1 2 3 4 5
# 6 7 8 9 10
# ...
# 16 17 18 19 20
# # 提示: print()  换行

i = 1
while i <= 20:
    print("%2d" % i, end=' ')  # print(i, end=' ')
    if i % 5 == 0: # if i == 5 or i == 10 or i == 15 or i == 20:
        print()
    i += 1
